This episode's opening scene, in which Harry Kim and Tom Paris hold an idle conversation before Chakotay calls them to the bridge, was filmed as part of Death Wish (1996), but later edited out and reused here due to its generic nature.
Carel Struycken who plays Spectre also played Mr. Homn in five episodes of Star Trek: The Next Generation (1987).
The outfit worn by Fear was designed to resemble brain matter, as Fear is a culmination of brain patterns from the Kohl survivors.
Thomas Kopache is one of only a few actors to appear on all four of the Star Trek TV spin-off series and is one of only five actors to play seven or more different characters in Star Trek - the others being Jeffrey Combs, Randy Oglesby, J.G. Hertzler, and Vaughn Armstrong.
Thomas Kopache played Mirok in The Next Phase (1992), Train Engineer in Emergence (1994), Enterprise-B communications officer in Star Trek: Generations (1994), Viorsa in Voyager "The Thaw", Kira Taban in Ties of Blood and Water (1997) and Wrongs Darker than Death or Night (1998), Tos in Broken Bow, Part 1 (2001) and a "canary in a coal mine" in Harbinger (2004).